Work machine

• US 9,212,469 B2
• Filed: 12/18/2012
• Issued: 12/15/2015
• Est. Priority Date: 12/22/2011
• Status: Active Grant

• Current Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Inventors: Udagawa, Tsutomu, Fujishima, Kazuo, Satake, Hidetoshi, Kunitomo, Yuichi, Ishikawa, Koji
• Primary Examiner(s): MUSTAFA, IMRAN K
• Application Number:
  US14/367,000
• Publication Number:
  US 20140371995A1
• Time in Patent Office: 1,092 Days
• Field of Search: 701/50
• US Class Current: 1/1
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 2200/40 Working vehicles
• CPC Class Codes: B60L 2210/40 DC to AC converters
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2240/443 Torque
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: B60L 7/14 for vehicles propelled by ac motors
• CPC Class Codes: E02F 9/123 Drives or control devices specially adapted therefor E02F9/125 and E02F9/128 take precedence
• CPC Class Codes: E02F 9/2025 Particular purposes of control systems not otherwise provided for E02F3/16, E02F3/26, sub-groups of E02F3/43, E02F3/651, sub-groups of E02F3/84, E02F3/907, E02F5/145 take precedence
• CPC Class Codes: E02F 9/2037 Coordinating the movements of the implement and of the frame
• CPC Class Codes: E02F 9/2058 Electric or electro-mechanical or mechanical control devices of vehicle sub-units for vehicles in general B60W
• CPC Class Codes: E02F 9/2095 Control of electric, electro-mechanical or mechanical equipment not otherwise provided for, e.g. ventilators, electro-driven fans control of hydraulic driven equipment E02F9/22
• CPC Class Codes: E02F 9/2285 Pilot-operated systems
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility

Abstract

There is provided a hydraulic excavator including a hydraulic pump (6) driven by an engine (7), a boom cylinder (3a) driven by hydraulic fluid delivered from the hydraulic pump (6), a swing motor (16) driven electrically, an operating device (4A) for operating the boom cylinder (3a), an operating device (4B) for operating the swing motor (16), and a vehicle body controller (11) which limits the power of the swing motor (16) in accordance with the operation amount of the operating device (4A) when the two operating devices (4A, 4B) are operated in combination. The power limit value of the swing motor (16) varies depending on the output of the engine (7). This allows a good operational feeling to be retained in combined operation regardless of the operating state of the engine.

Claims

1. A work machine comprising:

an engine;

a hydraulic pump driven by the engine;

a hydraulic actuator driven by hydraulic fluid delivered by the hydraulic pump;

an electric actuator driven electrically;

a first operating device which operates the hydraulic actuator;

a second operating device which operates the electric actuator, and

a control device configured to calculate a target speed of the electric actuator in accordance with an operation amount of the second operating device, calculate a speed limit value of the electric actuator by correcting the target speed in accordance with an operation amount of the first operating device, calculate a torque limit value in accordance with the operation amount of the first operation device, the torque limit value used as a maximum torque of the electric actuator during the operation of the electric actuator, control a torque generated by the electric actuator to be lower than the torque limit value, and control a speed of the electric actuator to be lower than the speed limit value, wherein

the control device is further configured to calculate a power required to drive the hydraulic actuator in accordance with the operation amount of the first operating device, calculate a power limit value in accordance with the power required to drive the hydraulic actuator, the power limit value capable of being supplied to the electric actuator for driving the electric actuator, select the smaller of the torque limit value and a torque resulting from torque conversion of the power limit value, generate a torque command for the electric actuator in accordance with the selected value, and output the torque command to the electric actuator.

2. A work machine according to claim 1, wherein

the first operating device is operable in two directions, and

the power limit value of the electric actuator has characteristics corresponding to a direction in which the first operating device is operated.

3. A work machine according to claim 1, wherein

the electric actuator is a motor, and

the power limit value of the electric actuator is set independently depending on whether the motor is in a powering or regenerative operation.